Combustion study of a spark-ignition engine from pressure cycles

Abstract

This work presents investigations on combustion analysis of an experimental spark-ignition engine fueled specially by a mixture of 15% in volume of hydrogen and 85% in volume of methane with an equivalence ratio of 0.67 at 100% load, corresponding to optimum conditions for SI engine, using two models, zero dimensional model based on Rassweiller & Withrow theory and first law-single zone either at constant or variable specific heat ratio of gases requiring experimental data of engine cylinder pressures. The results show the happening in the combustion chamber to the burning of real fuel with respect to time since the mass burned fractions and the heat release rate are evaluated. It can be seen that the two models have not the same rate of mass combustion during combustion process since it happens at different crank angles. The dependence of γ(T) is visible for high pressure since the variation of temperature exists and is not negligible. A comparison was attained between the results that used γ(T) with that used constant specific heat. A program in Fortran 77 has been developed for the complete simulations of SI engine combustion. The results are consistent with those found in the literature.